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Yes, it was my original plan, but it's only R22; and costs about $5000, also requires the underside to be fully stripped clean. I can get close to the same air seal, with mylar film, and tuck tape. But your thought process is spot on, and would give good results!

Adding more insulation, saves about $3000 when this mylar moisture barrier is used. I also get to leave the old insulation in place, for a little extra insulation buffer.

Oddly, I'll be working to exchange living space air; to ensure no moisture buildup inside! This air exchange will be through a temperature scavenger; that will recover conditioned air, to keep energy losses to a minimum. The incoming air will be drawn from an underground tube (an Earth Battery) so it will feed air at 59°F year round.

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